It’s All About the Core

or How to Estimate Compensation

by Sjaak Elmendorp

Originally published in American Lutherie #104, 2010



Ever since I started playing guitar, I’ve wondered why the saddles in my steel string guitars were set at some magical angle and, more puzzling, why the B string in my Martin D-28 (well, a cheap Japanese replica I have had for forty years now and still outbooms any guitar you want to bring to the bonfire) was about 10% sharp. After having accepted that this was one more quirk of the guitar-building community I had since joined, I got intrigued again when I set out to build a long-scale nylon-string acoustic bass (Photo 1) and, for the life of me, didn’t know what compensation to use.

The physics of the problem is very straightforward, but I found the mathematics employed to date rather inaccessible and the recipe for applying the developed theoretical frameworks not very clear. Given the fact that I once was a practicing physics PhD, I had to assume I wasn’t the only one wrestling with the question. Over the course of a long e-mail conversation with R.M. Mottola, for which I am very grateful, I was beginning to see some light at the end of the tunnel.